Electric water heater



Sept. 28, 1965 G, ELIAS 3,209,126

ELECTRIC WATER HEATER Filed Dec. 3, 1962 2 Sheets-Sheet 1 &

1x1 l 51 Q \Y\\\\ v .1 19 18 18 16 20 12 2 9 7 10 31 Fig! Sept. 28, 1965 G. ELIAS ELECTRIC WATER HEATER 2 Sheets-Sheet 2 Filed Dec. 5, 1962 United States Patent 5 Claims. (61. 219-309 My invention relates to electric water heaters, particularly those of the instantaneous type.

Such appliances generally are provided with an elec- .trically heated heat exchanger and a sensing member which closes and opens an electric switch in the energizing circuit of the heat exchanger in response to the flow of water occurring when a faucet or valve is opened and closed respectively.

As a rule, the individual components of such appliances are separately fastened on a mounting or base plate, and the heat exchanger, flow sen-sing member, and the interconnecting pipes and nipples "for passing water through the appliance are connected with each other by screw connections or soldered joints. The pipe and duct connections subjected as they are to alternating temperatures and resulting stresses during operation of instantaneous water heaters, are often the cause of failures. Soldered joints are superior and thus preferable in this respect, but involve manufacturing difficulties and render the appliance rather expensive.

It is an object of my invention to provide an electric water heater of the instantaneous type which readily and easily furnishes the necessary water conduits and their connection between the flow sensing member, the heat exchanger, and the inlet and outlet nipples and which assures reliable performance despite exacting operational requirements; and it is a conjoint object to provide such a water heater wherein the heat exchanger may be easily cleaned of any detrimetal depositions or residue with the aid of cleaning liquid, while reliably preventing any damage of the flow sensing member by ingress of the cleaning liquid or the retention of cleaning liquid in the outlet duct.

To achieve these objects, and in accordance with a feature of my invention, the heat exchanger of the water heater, preferably of the instantaneous type, and. a flow sensing member having an upper portion and a lower portion are provided with a base plate which is common to the heat exchanger and sensing member, and this base plate is provided with a cavity for accommodating the lower portion of the sensing member and has in its interior .a water inlet duct and a water outlet duct interconnected th-rough the heat exchanger, the interior of the base plate also containing pressure ducts through which the upper and lower portion of the sensing member communicate with respectively different localities of the water inlet duct. That is, the water inlet duct within the plate is preferably provided with a Venturi constriction or nozzle and the sensing member has a diaphragm between the chambers formed by the upper and lower portions respectively, these chambers being connected by the justmentioned pressure ducts with points that, due to the Venturi nozzle assume different pressures respectively when water flows through the appliance. I further provide the base plate with normally closed connecting means for passing cleaning liquid through the heat exchanger on a flow path which by-passes the How sensing memher, and I exchangeably fasten the heat exchanger as well as the upper portion of the sensing member to the common base plate in proper communicating relation to the inner duct system of the plate thereby completing the respective flow and pressure connections.

3,209,126 Patented Sept. 28, 1965' According to another feature of my invention, the connections of the base plate for passing cleaning liquid through the heat exchanger consists of threaded bores of which one communicates from the outside of the plate with the water inlet duct at a point between the heat exchanger and the sensing member, whereas the other bore of the plate communicates with the water outlet duct be-' tween the heat exchanger and the outlet nipple of the appliance. Normally the two threaded bores are closed by screw plugs and, for cleaning purposes, are exchangeable for respective screw nipples. Each of these nipples has a cylindrical, coaxial portion which covers the water inlet duct toward the sensing member or the water outlet duct toward the outlet nipple of the appliance when cleaning liquid is being passed through the threaded nipples in order to flush and clean the interior of the heat exchanger. The threaded nipples thus prevent the cleaning liquid from reaching the sensing members or the appertaining pressure ducts and also from escaping through the water outlet of the appliance.

The screw nipples are preferably provided with conical ends which sealingly protrude into the respective entrance and exit openings of the heat exchanger during cleaning operations.

According to still another feature of my invention, the normally closed bores of the common base plate for accommodating the above-mentioned cleaning nipples are located on one side of the plate, whereas the heat exchanger and the upper portion of the sensing member are mounted on the opposite plate side in spaced relation to each other and the plate is provided with .a heat insulating slot between the heat exchanger and sensing member. The top portion of the plate is preferably kept substan-l tial-ly planar, with the exception of the above-mentioned cavity for the sensing member and the duct openings, and the various ducts for water as well as the cleaning bores and the water inlet and outlet openings are located in longitudinal and transverse ribs or bulges that protrude on the opposite side of the plate.

The above-mentioned and other features of my invention will be apparent from the embodiment of an electric instantaneous water heater illustrated by way of example on the accompanying drawings in which:

FIG. 1 shows the water heater, partly schematically, in section.

FIG. 2 shows the same water heater provided with screw nipples instead of plugs for passing cleaning liquid through the heat exchanger.

1FIG. 3 is a perspective view onto the top of the base p ate.

FIG. 4 is a perspective view onto the bottom side of the base plate; and

FIG. 5 shows one of the threaded nipples used for cleaning the heat exchanger.

The illustrated water heater comprises a base plate 1 consisting of a metal casting which contains in its interior the majority of the ducts and channels required for the operation of the appliance. The top surface of the base plate 1 is generally planar but is provided with a circular cavity 2 which forms part of the lower portion of a pressure sensing member. The cavity is covered by a diaphragm 3 adjacent to the upper portion of the sensing member. The upper portion is formed essentially by a mirror-image cavity 4 in a metal plate 5. The diaphragm 3 carries a vertical pin 6 which passes through an opening of the plate 5 to the outside and serves to actuate an electric switch in response to an occurrence of a pressure difference between chambers 2 and 4, resulting from the flow of water through the appliance.

The chamber 2 in the lower portion of the sensing member communicates through a pressure duct 7 with a water inlet duct 9 within the base plate 1. Theinlet duct 9 is connected with a water inlet 10 formed by a threaded bore for attachment to a supply of water under pressure and shown provided with a lateral control member 38.

The chamber 4 in the upper portion of the sensing member communicates through a duct with the interior of a Venturi member 12 inserted into the inlet duct 9. The pressure duct 8 extends partly within the base plate 1 and partly within the plate-shaped upper portion 5 of the sensing member.

When Water is being drawn through the heat exchanger, the pressure ducts 7 and 8 are subjected to respectively different pressures due to the presence of the Venturi nozzle member 12, so that the diaphragm 3 is deflected and actuates the before mentioned electric switch (not shown) which then closes the electric circuit of the heat exchanger.

The heat exchanger 21, schematically represented, comprises a dome-shaped structure whose interior is provided with a water guiding helix 24 and which is externally surrounded by an electric heater coil 25. The heat exchanger is welded or hard soldered to a foot plate 23 and fastened to the top surface of the base plate 1 by means of bolts 13. Similar bolts 13 secure the plate-shaped upper portion 5 of the sensing member to the plate in spaced relation from the foot plate 23 of the heat exchanger. The junction between heat exchanger and base plate, as well as between the top portion 5 of the sensing member and the base plate, is liquid-tight. The base plate 1 has a slot 14 between the heat exchanger and the sensing member for minimizing heat transfer.

The base plate 1 is further provided with a threaded portion 31 at the outer end of the water inlet duct 9 for the purpose of permitting the insertion or exchange of the Venturi nozzle 12. Another threaded bore 16 is located coaxially beneath the heat exchanger and communicates with an inlet pipe 20 extending into the upper portion of the heat exchanger. Located in the outlet portion of the base plate 1 is an outlet duct 22 which connects the lower portion of the heat exchanger with a threaded bore 17 of the base plate laterally in communication with the outlet opening 19.

Normally the bores 11, 16, 17 and 31 are tightly closed and sealed by means of threaded lugs 38, 18 and 37 respectively.

The above-mentioned ducts and connections are located in a longitudinal rib 26 (FIG. 3, 4), transverse ribs 27, 28 and in projecting portions of the base plate 29, 30 that form part of the ribs. Integral lug portions 32 and 33 of the base plate are provided with bores 34 and 35 respectively by means of which the base plate is fastened in the housing (not illustrated) of the appliance.

When the heat exchanger 21 is to be cleaned from lime depositions and other incrustation or precipitation by passing chemically active cleaning liquid through the interior of the heat exchanger, the plugs 18 are removed from the respective bores 16, 17 and substituted by respective plug nipples 15 (FIGS. 2, 5). Each of these nipples is provided with a nut portion 39, a conical sealing portion 40 at the inner end, a cylindrical plug portion 41 between nut 39 and conical end 40, and an external nipple portion 42 for attachment of a hose. The nipple plug consists of an integral single piece and is axially traversed by a bore 43.

During normal use the appliance corresponds to FIG. 1 of the drawing. The water enters through the pressure connection and the inlet duct 9, the nozzle 12, bore 16 and inlet tube 20 through the heat exchanger 21, thence through outlet duct 22 and the outlet bore 19.

When it becomes necessary to clean the heat exchanger, the appliance need not be dis-connected from the water line. It is only necessary to substitute the two plugs 18 by the nipple plugs 15. Simply by screwing the nipples into the respective bores, the conical ends of the nipples become forced into the entrance and exit openings of the heat exchanger while the cylindrical portions 41 of the plugs cover the inlet duct 9' and the outlet duct of the base plate. As a result, the flow sensing member is reliably prevented from ingress of cleaning liquid and the cleaning liquid is prevented from escaping through the water outlet of the appliance.

While a particular embodiment of the invention has been described in detail it will be obvious to those skilled in the art that the invention may be otherwise embodied within the scope of my invention.

I claim:

1. A water heater comprising a heat exchanger having means defining a water flow path therethrough and means for heating the water in said flow path, a base plate removably carrying said heat exchanger and formed with a water inlet duct and an outlet connected respectively to the ends of said flow path, a flow sensing member comprising a lower chamber formed by a cavity in said base plate and an upper chamber removable from said lower chamber, said chambers being separated by a flexible diaphragm and communicating with different localities of said inlet duct, means located in said inlet duct for creating a pressure difference between said diflerent localities when water is flowing in said inlet duct whereby said chambers are subjected to different pressures respectively and said diaphragm is deflected, means actuated by the deflection of said diaphragm for activating the heating means of said heat exchanger to heat the water in said flow path, connecting means in said base plate communicating with the end of said flow path that is connected to said inlet duct at a location downstream from said flow sensing member, said connecting means having an exteriorly open end, a removable closure member normally closing said open end, and means replacing said removable closure member for supplying cleaning liquid to said connecting means, said cleaning liquid supplying means being insertable in said open end so as to block the flow of cleaning liquid through the inlet duct in a direction toward said flow sensing member whereby cleaning liquid is passed through said heat exchanger and bypasses said flow sensing member.

2. In a water heater according to claim 1, said base plate having a substantially planar top surface on which said heat exchanger and said upper chamber of said sensing member are mounted, said cavity extending from said top surface into said plate, and said plate having rear bulges within which said inlet duct and said pressure ducts and connecting means are located.

3. A water heater comprising a heat exchanger having means defining a water flow path therethrough and means for heating the water in said flow path, a base plate removably carrying said heat exchanger and formed with a water inlet duct and an outlet connected respectively to the ends of said flow path, a flow sensing member comprising a lower chamber formed by a cavity in said base plate and an upper chamber removable from said lower chamber, a flexible diaphragm disposed between and separating said chambers, a pressure duct connecting each of said chambers with a different locality of said inlet duct, means located in said inlet duct for creating a pressure difference between said different localities when Water is flowing in said inlet duct whereby said chambers are subjected to different pressures respectively and said diaphragm is deflected, means actuated by the deflection of said diaphragm for activating the heating means of said heat exchanger to heat the water in said flow path, said base plate being formed with a pair of threaded bores, one of said bores communicating with said inlet duct between one end of said heat exchanger flow path and said pressure ducts, said other bore communicating with the other end of said heat exchanger flow path, two removable plugs normally threaded in said bores respec tively for closing the same, and nipple means replacing said removable plugs and insertable in said bores fordelivering cleaning fluid to said inlet duct and discharging: the same from the other end of said heat exchanger flow path respectively, said nipple means when inserted in said bores simultaneously blocking the flow of cleaning fluid through said inlet duct in a direction toward said flow sensing member whereby cleaning fluid is passed through the flow path of said heat exchanger and bypasses said flow sensing member.

4. In a water heater according to claim 3, said heat exchanger and said sensing member being mounted in mutually spaced relation on one side base plate, said two bores being located on the opposite side, and said base plate having a heat insulating slot on said one side between said heat exchanger and said sensing member.

5. A water heater comprising a heat exchanger having means defining a water flow path therethrough and means for heating the water in said flow path, a base plate removably carrying said heat exchanger and formed with a water inlet duct and an outlet connected respectively to the ends of said flow path, a flow sensing member com prising a lower chamber formed by a cavity in said base plate and an upper chamber removable from said lower chamber, a flexible diaphragm disposed between and separating said chamber, a pressure duct connecting each of said chamber with a different locality of said inlet duct, means located in said inlet duct for creating a pressure diflerence between said different localities when water is flowing in said inlet duct whereby said chambers are subjected to dilferent pressures respectively and said diaphragm is deflected, means actuated by the deflection of said diaphragm for activating the heating means of said heat exchanger to heat the water in said flow path, said base plate being formed with a pair of threaded bores, one of said bores communicating with said inlet duct between one end of said heat exchanger flow path and said pressure ducts, said other bore communicating with the other end of said heat exchanger flow path, two removable plugs normally threaded in said bores respectively for closing the same, two threaded nipples exchangeable for said plugs in said respective bores for passing cleaning liquid through said heat exchanger, said nipples having axial portions respectively blocking said outlet and a portion of said inlet duct including said diflerent localities from said flow path when said nipples are seated in said bores, and each of said nipple portions having a conical sealing and adjacent to the heat exchanger when the nipples are so seated.

References Cited by the Examiner UNITED STATES PATENTS 1,920,284 8/33 Wells 219-309 2,673,919 3/54 Arvins et a1. 219--302 3,005,888 10/61 Putz 219-322 X 3,088,017 4/63 Schomann 219309 X RICHARD M. WOOD, Primary Examiner.

ANTHONY BARTIS, Examiner. 

1. A WATER HEATING COMPRISING A HEAT EXCHANGER HAVING MEANS DEFINING A WATER FLOW PATH THERETHROUGH AND MEANS FOR HEATING THE WATER IN SAID FLOW PATH, A BASE PLATE REMOVABLY CARRYING SAID HEAT EXCHANGER AND FORMED WITH A WATER INLET DUCT AND AN OUTLET CONNECTED RESPECTIVELY TO THE ENDS OF SAID FLOW PATH, A FLOW SENSING MEMBER COMPRISING A LOWER CHAMBER FORMED BY A CAVITY IN SAID BASE PLATE AND AN UPPER CHAMBER REMOVABLY FROM SAID LOWER CHAMBER, SAID CHAMBERS BEING SEPARATED BY A FLEXIBLE DIAPHRAGM AND COMMUNICAING WITH DIFFERENT LOCALITIES OF SAID INLET DUCT, MEANS LOCATED IN SAID INLET DUCT FOR CREATING A PRESSURE DIFFERENT BETWEEN SAID DIFFERENT LOCALITIES WHEN WATER IS FLOWING IN SAID INLET DUCT WHEREBY SAID CHAMBERS ARE SUBJECTED TO DIFFERENT PRESSURES RESPECTIVELY AND SAID DIAPHRAGM IS DEFLECTED, MEANS ACTUATED BY THE DEFLECTION OF SAID DIAPHRAGM FOR ACTIVAING THE HEATING MEANS OF SAID HEAT EXCHANGER TO HEAT THE WATER IN SAID FLOW PATH, CONNECTING MEANS IN SAID BASE PLATE COMMUNICATING WITH THE END OF SAID FLOW PATH THAT IS CONNECTED TO SAID INLET DUCT AT A LOCATION DOWNSTREAM FROM SAID FLOW SENSING MEMBER, SAID CONNECTING MEANS HAVING AN EXTERIORLY OPEN END, A REMOVABLY CLOSURE MEMBER NORMALLY CLOSING SAID OPEN END, AND MEANS REPLACING SAID REMOVABLY CLOSURE MEMBER FOR SUPPLYING CLEANING LIQUID TO SAID CONNECTING MEANS, SAID CLEANING LIQUIUD SUPPLYING MEANS BEING INSERTABLE IN SAID THROUGH END SO AS TO BLOCK THE FLOW OF CLEANING LIQUID THROUGH THE INLET DUCT IN A DIRECTION TOWARD SAID FLOW SENSING MEMBER WHEREBY CLEANING LIQUID IS PASSED THROUGH SAID HEAT EXCHAMGER AND BYPASSES SAID FLOW SENSING MEMBER. 